1. Field of the Invention
This invention relates in general to evaporative coolers and more particularly to improved trough structures for distributing water to the cooler pads used in evaporative coolers.
2. Description of the Prior Art
Evaporative cooler structures have long been used primarily in hot relatively dry climates, to provide a low cost way of cooling both residential and commercial buildings.
Evaporative coolers have traditionally been in the form of box-shaped cabinets having open sides in which wettable cooler pads are demountably carried. An air handler mechanism, usually in the form of a centrifugal blower, is mounted within the cabinet and is operated to exhaust air therefrom. This creates a negative static pressure within the cabinet which causes hot ambient air to move through the wettable cooler pads into the cabinet and subsequently to be exhausted therefrom by the air handler mechanism. The air moving through the wettable cooler pads is cooled by the well known evaporation principle and this cooled air is supplied by the air handler to a point of use, such as by means of suitable ducting network.
In addition to the above described air moving sub-system, evaporative coolers all include a water supply sub-system and in most cases, this sub-system has a water recirculation capability. In a typical evaporative cooler, the bottom of the cabinet is in the form of a pan for containment of a water supply used in operating the cooler. A float controlled water shutoff valve is mounted in the floor plan and is coupled to a source of water such as a municipal water supply line. The float controlled water shutoff valve will operate to initially supply water to the floor pan and is intermittently opened, under control of the float, to supply make-up water to replace that lost as a result of the evaporation process.
A suitable pump is mounted in the floor plan of the evaporative cooler and is operated to supply water through a suitable plumbing network to the top of each of the wettable cooler pads. The water provided to the tops of the cooler pads is caught in a water distribution trough which forms the upper part of the pad frame in which a suitable wettable medium, such as excelsior, is contained. The water distribution trough distributes the water along the top of the wettable medium so that it flows downwardly under the influence of gravity through the medium and thereby comes in contact with the air being drawn into the cabinet through the medium. Such air and water contact causes the evaporation needed to cool the air and this, of course, causes the above mentioned loss of water. The water which is not lost to evaporation will drop from the bottom of the cooler pads into the floor pan for recirculation by the pump.
Traditionally, the prior art water distribution troughs are elongated sheet metal structures defining a single V-shaped in cross section channel extending longitudinally thereof, with a plurality of teardrop-shaped water outlet slits formed in spaced apart increments along the length of the channel. The slits are located in one of the walls which define the V-shaped cross sectional channel with the lower open ends of the slits being spaced upwardly from the bottom of the channel.
The movement of air through the wet cooler pads will deflect the water from a natural vertical flow down through the pads into one which causes the water to move toward the air outlet face as it nears the bottom of the pads. In most evaporative coolers of what are considered as being of a residential size, deflected water movement does not cause a problem. However, in evaporative coolers of the type commonly referred to as industrial size coolers, water deflection will prevent the water from reaching the lower ends of the pads due to the increased height of the cooler pads used in industrial size coolers.
To alleviate the water deflection problem, it is a common practice of manufacturers of such industrial size coolers to employ a second trough at a point intermediate top and bottom of the cooler pads to catch the water as it nears the air outlet face and direct it back into the middle of the pads. The second or lower, trough cannot be attached to the cooler pad frame in the same manner as the top trough and thus must be of a different configuration. This increases the tooling costs in addition to the costs for the trough itself and the additional manufacturing time and labor.
During operation of the evaporative cooler, the water, which inherently contains minerals, such as sodium and calcium chlorides and other impurities, will increase as to the concentration of those minerals and other impurities as a direct result of evaporation. As the mineral concentration increases, the rate of precipitation will also increase, and this results in mineral deposition, or scaling, of virtually every component of the evaporative cooler, and this problem is of particular concern in all the parts of the cooler having direct contact with the water.
In addition to the mineral build-up and resulting scaling problem, other contaminants will collect in the water supply as a result of the air washing effect which occurs when the air comes into contact with the water in the cooler pads. A relatively large quantity of contaminants, such as airborne dust, pollen, and the like, will be washed out of the ambient air as it passes through the wet cooler pads, and those contaminants are carried throughout the cooler by the recirculating water supply.
One area of evaporative coolers which is effected by the mineral build-up and other contamination problems in evaporative coolers is the water distribution trough. Mineral deposition will occur particularly in the immediate area of the water outlet slits and will gradually reduce the size of the outlets and thus reduce the water flow therethrough. As the size of the water outlet slits is reduced, other contaminating materials, such as the above mentioned pollen, dust, and the like, will tend to become caught in the outlet slits thus reducing water flow therethrough. When this begins to occur, the wettable medium will develop dry spots which has a detrimental effect on the cooling efficiency of the evaporative cooler. As the outlet slits becomes progressively smaller, the outlet flow rate of the troughs will become less than the input flow rate of the water received from the cooler's plumbing system and overflowing can result.
Due to the prior art pad frame and water distribution trough configurations, no provision is made to allow a single top mounted water distribution trough to be used in all the cooler pad assemblies of various sizes of evaporative coolers. And, the prior art water distribution troughs make no provisions for handling water outlet clogging problems and the overflow problem.
Therefore, a need exists for a new and improved water distribution trough for use in the evaporative cooler pad assemblies of evaporative coolers.